1. Field of the Invention
The invention relates to the filed of micromachining electromagnetic devices, and in particular, a micromachined magnetic actuator and a method for releasing the magnetic actuator from its parent wafer.
2. Description of the Prior Art
It is generally known that magnetic actuation provides stronger forces over a longer distance as compared to electrostatic driving mechanisms. See W. Gu et al., AIAA Journal. Vol. 31, No. 7, pp 1177-86 (1993); and K. Rinoie, Aeronautical Journal, Vol. 97 (961), pp 33-38 (1993). Electromagnetic driving may be used as the motive force in many different configurations, such as shown by I. J. Busch-Vishniac, Sensors and Actuators, A33 at 207-20 (1992); and C. H. Ahn et al., IEEE J. Microelectromechanical Systems, Vol. 2 (1) at 15-22 (1993), even in combination with the electrostatic forces, H. Guckel et al., 1993 IEEE Workshop on Microelectromechanical Systems at 7-11 (1993). The introduction of electrochemical deposition of Permalloy (e.g. 50/50 FeNi) has dramatically increased the power of electromagnetic driving mechanisms and efficiency of magnetic actuators as described in B. Wagner et al., Sensors and Actuators, A(32) at 598-03 (1982); C. Liu et al., 1994 IEEE Workshop on Microelectromechanical Systems at 57-62 (1994); and S. W. Yuan, Foundations of Fluid Mechanics, Prentice Hall (1972).
What is needed is a design for a micromachined micromagnetic actuator which can be made by surface micromachining and which are adapted to be reproduced in large scale arrays.
As will be described below, the illustrated embodiment of the invention is discussed generally, then specifically, in any array applied to a delta wing. The delta wing is one of the fundamental configurations for generating lift forces and its aerodynamic control is a design feature of great importance. When airflow hits the two leading edges of the wing at a certain angle of attack, two counter-rotating leading edge vortices are separated from the laminar flow and propagate over the wing's top surface. The two high momentum, low pressure vortices contribute identical vortex lifting forces on the two sides of the wing, the sum of these being about 40 percent of the total lifting forces. The strength and position of these two vortices are determined by the boundary layer conditions near their separation points. The boundary layer is roughly 1 to 2 millimeters thick at wind tunnel flow speeds of less than 20 meters per second. The thickness will decrease when the flow speed is increased.
What is needed then is some means of controlling these vortices in order to provide a control function for delta wing.